feat(3a): Admin-Struktur aufgeräumt + Restart nach „Wartung"

- 4 ruhige Top-Tabs: Übersicht · Nutzer · System · Konfiguration.
- „Notrufe" wandert unter System; „Metriken" → „Nutzungs-Statistik" unter
  Nutzer einsortiert.
- Status ist jetzt rein lesend (Wartung + DB-Backup raus).
- Neuer „Wartung"-Abschnitt unter Konfiguration mit prominentem
  „Gateway neu starten" + DB-Backup. app.js v=46.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/web/index.html

@@ -42,7 +42,6 @@
     <nav class="shrink-0 flex border-b border-slate-200 dark:border-slate-700 bg-white dark:bg-slate-800 overflow-x-auto">
       <button class="admin-tab px-4 py-3 text-sm font-medium whitespace-nowrap border-b-2 border-transparent text-slate-500 hover:text-slate-700 dark:text-slate-400 dark:hover:text-slate-200 transition-colors" data-tab="overview">📊 Übersicht</button>
       <button class="admin-tab px-4 py-3 text-sm font-medium whitespace-nowrap border-b-2 border-transparent text-slate-500 hover:text-slate-700 dark:text-slate-400 dark:hover:text-slate-200 transition-colors" data-tab="users">👥 Nutzer</button>
-      <button class="admin-tab px-4 py-3 text-sm font-medium whitespace-nowrap border-b-2 border-transparent text-slate-500 hover:text-slate-700 dark:text-slate-400 dark:hover:text-slate-200 transition-colors" data-tab="emergency">🚨 Notrufe</button>
       <button class="admin-tab px-4 py-3 text-sm font-medium whitespace-nowrap border-b-2 border-transparent text-slate-500 hover:text-slate-700 dark:text-slate-400 dark:hover:text-slate-200 transition-colors" data-tab="system">🖥 System</button>
       <button class="admin-tab px-4 py-3 text-sm font-medium whitespace-nowrap border-b-2 border-transparent text-slate-500 hover:text-slate-700 dark:text-slate-400 dark:hover:text-slate-200 transition-colors" data-tab="config">⚙ Konfiguration</button>
     </nav>
@@ -180,6 +179,16 @@
         </div>
       </div>
 
+      <!-- ── Tab: Wartung ── -->
+      <div id="admin-tab-maintenance" class="hidden h-full overflow-y-auto p-4">
+        <div class="max-w-3xl mx-auto">
+          <h3 class="font-semibold text-base mb-4">Wartung</h3>
+          <div id="maintenance-content" class="space-y-4">
+            <p class="text-sm text-slate-400">lade …</p>
+          </div>
+        </div>
+      </div>
+
       <!-- ── Tab: Log ── -->
       <div id="admin-tab-log" class="hidden h-full flex flex-col">
         <div class="shrink-0 flex items-center gap-3 px-4 py-2.5 border-b border-slate-200 dark:border-slate-700 bg-slate-50 dark:bg-slate-800/60">
@@ -356,6 +365,6 @@
     <div id="status" class="w-full max-w-3xl mx-auto mt-1 min-h-[1rem] text-xs text-slate-500 dark:text-slate-400"></div>
   </footer>
 
-  <script src="/app.js?v=45"></script>
+  <script src="/app.js?v=46"></script>
 </body>
 </html>